Sunday, June 3, 2018

Guatemala, Day 14

A relative of someone I know took this photo
of Volcan de Fuego today.
Today's big news is that a volcano near Antigua erupted pretty dramatically today. Several people died and hundreds were injured. Luckily its nowhere near where I am but it may impact my family's arrival on Saturday, as well as some of our vacation plans. Pretty nuts.

Our program is going well. We had lectures about suction pumps, ventilators, anesthesia machines, and medical gasses, and we started working on building our power supplies. We'll be spending lab this week making them into variable DC power supplies suitable for actual use! On Friday I took a group of five students back to the public Occidental hospital to work on more equipment. Apparently I had come away with an unrealistically rosy picture of the hospital last week. My host family assured me that despite some newer equipment, the hospital is poor and underequipped. Families of inpatients are often given prescriptions and told to go buy the meds at a pharmacy because they aren't available in the
hospital. Anyone who can afford it goes to the private hospitals. I haven't been to any but I'm told they're pretty nice. With that said, villagers sometimes travel for hours on end to visit the public hospital and their families even camp out front if they have nowhere else to stay.

Laundry air-drying at the hospital.
We spent a good chunk of the day back in the odontology office. We were trying to fix two things - a small autoclave which was on the fritz and the suction system which wasn't quite working right. They have three dental chairs but the suction mechanism (for sucking up saliva and blood from the mouth) on one of them hadn't worked for four years! We started by looking at the compressors to make sure they were working properly. They have two compressors tied together without the use of any check valves or anything, which seemed a bit fishy to me. I wasn't sure if that was causing any problems so I spent a good hour plus messing around with them. Eventually I determined that the suction problem in the clinic still existed if I only used a single compressor. Furthermore, I decided that I could probably tie them together if I set the tank pressures as close together as possible. If you don't do this, then one compressor tries to fill up the other one and it gets messy. All of this was made massively more complicated by the fact that none of the plastic tubing they had was the right size to fit any of the nozzles, so moving and testing different configurations took a lot of doing just to get things airtight. We resorted to using a lighter to melt the tubing a little so it would wiggle down on the various nozzles. After that we started debugging why there was no suction at the one chair. It didn't help things whatsoever that neither me nor any of my students know how the suction and water on a dental chair are connected.
Lots of tubing to sort out.

The yellow line holds pressurized air (from the compressor) and the green line is the suction. High speed air blows past the suction tube and into the drain (at left). As the air draws across the port to the suction tube, it creates negative pressure.

But as engineers are wont to do, we worked to isolate the problem - tracing the air lines to see how far the pressurized air was getting. We had to take some of the dental chair apart to do this but in the end we discovered a pretty elegant mechanism. The pressurized air is forced through a very narrow channel. On the side of that channel there is an outlet port that connects to the suction tube. As the pressurized air flows past that port at high speeds, it creates negative pressure, which is the source of suction. All the liquids that are sucked up by the suction get pulled through that port and whooshed into a drain in the floor. Everything seemed to be mostly in order so we tried to clean all the tubing and valves as best we could, suspecting a small clog was to blame. Eventually we got it all back together and lo and behold: suction! The dentist was besides himself and was very grateful. I had a lot of fun because I got to take something apart and learn how it works. And the students had fun watching and learning too. Good times. The only downside was that I got really dirty. There is some unspeakable funk lurking inside tubes and valves that don't get cleaned very often. Needless to say I took an aggressive shower when I got home.

Earlier today I went to a barbecue fundraiser for an Australian lady who lives in town. She shelters dogs and has a monthly cookout to raise money for their care. I had an incredibly delicious plate of ribs and beans. I also got to taste an unusual drink. I don't remember what its called but its basically a Bloody Mary with beer instead of vodka. I enjoyed it - very refreshing and just perfect to wash down the ribs.
This very adorable creature wanted to share my ribs.

A very satisfying lunch!

No comments:

Post a Comment